Basin inversion: reactivated rift structures in the central Ligurian Sea revealed using ocean bottom seismometers

Abstract. The northern margin of the Ligurian Basin shows notable seismicity at Alpine front, including frequent magnitude 4 events. Seismicity decreases offshore towards centre and Corsica, revealing a diffuse distribution low-magnitude earthquakes. We analyse data amphibious AlpArray seismic network with focus on component, ocean bottom seismometer (OBS) network, consisting 24 broadband OBSs deployed for 8 months, to reveal depth micro-earthquakes beneath Sea. Two clusters occurred between ∼ 10 km 16 below sea surface, within lower crust uppermost mantle. Thrust faulting focal mechanisms indicate compression an inversion Basin, which is abandoned Oligocene–Miocene rift basin. basin suggested be related Africa–Europe plate convergence. locations suggest reactivation pre-existing rift-related structures. Slightly different striking directions presumed faults in compared further east hence away from may reflect counter-clockwise rotation Corsica–Sardinia block. High mantle S-wave velocities low Vp/Vs ratio support hypothesis strengthening during rifting-related extension thinning continental crust.